how do you convert this code to nodes?
Your question is very specific. However, converting code into nodes is precisely what the Dynamic Maths Expression / Node Expressions was made for (download it from https://github.com/baldingwizard/Blender-Addons/wiki/Dynamic-Maths-Expression).
Once you've installed the add-on you should have a new Maths Expression option in the node 'Add' menu.
Create a new text block and paste the following code :
outputs(output)

xform[] = combine(zero, one - zero)

in_value = remap_input
                            
output = combine(clip(xform[x] + xform[y] * in_value), clip(min), clip(max))

(NOTE: The above text is translated directly from your sample code, almost line for line)
Name the textblock something meaningful (eg, 'mycode'), go to the Node Editor and add a new Maths Expression with the text TEXT:&lt;name&gt; (replacing &lt;name&gt; with the name of your text block - eg, 'TEXT:mycode') and the add-on will interpret your code and generate a new node group containing the relevant nodes to implement the code.
Obviously your coder friend will need to produce code in the correct syntax for the add-on to interpret.